Interaction with garbage collector?

[MilesCranmer]

I'm wondering if the various macros should interact with Julia's GC at all. For example, the Lifetime object is actually aware of all the references created in its scope:

mutable struct Lifetime
    const immutable_refs::Vector{Any}
    const immutables_lock::Threads.SpinLock
    const mutable_refs::Vector{Any}
    const mutables_lock::Threads.SpinLock
    @atomic expired::Bool

    Lifetime() = new([], Threads.SpinLock(), [], Threads.SpinLock(), false)
end

and so when cleanup!(lifetime) is called, it could call the finalizers automatically. Which would be very rust-like.

But I'm not sure if this is the direction we want to go because I'm not expecting the borrow checker code to ever be faster than plain Julia. Not sure though.

@MasonProtter do you know if the compiler escape analysis tools will ever be used to free objects without needing the garbage collector? In other words, get more rust-style memory management?

[MilesCranmer]

Actually it looks like a very basic version of this is already done? JuliaLang/julia@c4effda

Although using EscapeAnalysis for this was abandoned: JuliaLang/julia#44056.

[oscardssmith]

Although using EscapeAnalysis for this was abandoned: JuliaLang/julia#44056.

Not abandonded, merged: JuliaLang/julia#45272.

[MasonProtter]

The problem with Eager Finalizer Insertion is that it cant do stuff that has certain Effects as that would taint the Effects of the function that the finalizer is inserted into. That's why it refuses to e.g. insert a Libc.free finalizer eagerly.

We could be more aggressive if we wanted to though